The Application of Quantitative H-NMR for the Determination of Melatonin and Vitamin B6 in Commercial Melatonin Products.

Melatonin supplements have been widely used to improve sleep quality and overcome sleep disorders, with melatonin and vitamin B6 serving as the primary active ingredients. This study developed a novel analytical method for the simultaneous quantification of melatonin and vitamin B6 using H-NMR spectroscopy. The characteristic signals of melatonin and vitamin B6 hydrochloride at δ 7.09 ppm and δ 8.12 ppm were selected for quantitative analysis, with maleic acid used as the internal standard. The method was validated for specificity, precision, and stability. The results demonstrate that the method exhibits high precision and complies with the guidelines established by the China Food and Drug Administration (CFDA). Furthermore, this method has been successfully applied to commercially available formulations. Compared to conventional methods, the H-NMR technique offers a more efficient and simpler alternative, making it suitable for the simultaneous quantitative determination of melatonin and vitamin B6 hydrochloride. This approach ensures the quality, stability, and safety of commercial melatonin products.